export default `czm_material czm_getMaterial(czm_materialInput materialInput){ 
    czm_material material = czm_getDefaultMaterial(materialInput); 
    material.diffuse = 1.5 * color.rgb; 

    vec2 st = materialInput.st; 
    float dis = distance(st, vec2(0.5, 0.5)); 

    float per = fract(time); 
    if (dis > per * 0.5) { 
        //material.alpha = 0.0;
        discard;
    }else {
        material.alpha = color.a  * dis / per / 2.0;
    }
    return material;
}`;
